Suspension system for a transport vehicle

ABSTRACT

A suspension system for a multi-axle transport vehicle for moving heavy loads includes two fluid activated cylinders and two spaced apart arms for each wheel and axle set which allow the transport vehicle to be raised and lowered with respect to the roadway. The suspension system mechanically stabilizes the axles with respect to the transport vehicle thereby reducing axle yaw and allowing higher transport speeds.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the filing benefit under 35 U.S.C. § 119(e) ofU.S. Provisional Application No. 60/383,554, filed May 24, 2002, whichis included herein by reference.

TECHNICAL FIELD

The present invention pertains generally to multi-axle transportvehicles for moving heavy loads, and more particularly to a suspensionsystem for such vehicles.

BACKGROUND OF THE INVENTION

Heavy hauling vehicles for moving transformers, cranes, boats,industrial equipment, and other heavy objects are well known in the art.An example of such a vehicle is given in U.S. Pat. No. 4,943,078 whichdiscloses a heavy load hauler for traveling on conventional roadways formoving heavy construction equipment such as cranes or the like from onework site to another. The hauler includes a front tractor drawncarriage, a rear carriage, and a load unit disposed between and carriedby the carriages. The front carriage is supported upon a multiplicity ofindependent wheel and axle units. There is a first fifth wheel couplingat the leading end of the front carriage for connecting to the fifthwheel coupling of a tractor. A second fifth wheel coupling is spacedrearwardly. The load carrying rear carriage is also supported upon amultiplicity of independent wheel and axle units. There is a fifth wheelcoupling intermediate the leading and trailing ends of the carriage. Theload unit has forwardly and rearwardly projecting goosenecks. Eachgooseneck has a fifth wheel coupling. The one on the forwardlyprojecting gooseneck connects to the fifth wheel coupling on the frontcarriage. The one on the rearwardly projecting gooseneck connects to thefifth wheel coupling on the rear carriage. The load unit may be eitherthe crane itself or a flatbed upon which the crane is carried. At leastsome of the independent wheel and axle units are steerably mounted ontheir carriages. Each wheel and axle unit has its wheels supported by ahydraulic suspension. Hydraulic circuitry interconnects all of thesuspensions so as to equally distribute the load among all of the wheelunits. Steering of the independent wheel and axle units is interphasedfor the front and rear carriages by a pair of operatively associatedinterrelated inline valve cylinder units. FIG. 12A shows a valve 718used in a power steering system which is coupled to a connecting link703.

Other heavy hauling vehicles are sold by Goldhofer Fahrzeugwerk G.m.b.H.of Memmingen, Germany; Nicolas of Champs Sur Yonne, France; and Talbertof Rensselaer, Ind.

Improved systems having automatic steering at all speeds and suspensionsystems that respond rapidly to the varying road conditions imposed byhigher speeds would greatly reduce the time and effort required to movethe vehicle to the load, move the load, and return the vehicle tostorage.

SUMMARY OF THE INVENTION

The present invention is directed to a suspension system for a heavyload transport vehicles which tends to resist axle yaw. The body of thesuspension system is connected to the axle by an axle linkage memberwhich is connected to the body at four different pivotal locations. Thisfour-point connection stabilizes the axle linkage member andsubstantially reduces any tendency to yaw when exposed to road inducedforces. The suspension system employs two fluid activated cylindersrather than the conventional one cylinder. This feature allows the useof smaller diameter cylinders for a given system pressure. The cylindersare mounted on the outside of the suspension system for ease ofmaintenance.

In accordance with a preferred of the invention, a suspension system fora transport vehicle includes a body which is pivotable about a firstaxis, the body has a first attachment station separate and spaced apartfrom a second attachment station. An axle is disposable along a secondaxis which is perpendicular to the first axis. An axle linkage memberhas a third attachment station which is spaced apart from a fourthattachment station, the third attachment station of the axle linkagemember is pivotally connected to the first attachment station of thebody, and the fourth attachment station of the axle linkage member ispivotally connected to the second attachment station of the body. Theaxle linkage member is pivotable about a third axis which is parallel tothe second axis. The axle is pivotally connected to the axle linkagemember; the axle is pivotable about a fourth axis perpendicular to thefirst, second and third axes. Two separate and spaced apart fluidactivated cylinders are pivotally connected between the body and theaxle linkage member, wherein the two fluid activated cylinders aredisposed outside of the first, second, third, and fourth attachmentstations. When the two fluid activated cylinders are extended, the axlelinkage member pivots away from the body. When the two fluid activatedcylinders are retracted, the axle linkage member pivots toward the body.

In accordance with an aspect of the invention, when the transportvehicle is traveling on a road, the connection of the first attachmentstation to the third attachment station, the connection of the secondattachment station to the fourth attachment station, and the connectionof the two fluid activated cylinders between the body and the axlelinkage member combine to reduce yaw of the axle.

Other aspects of the present invention will become apparent from thefollowing detailed description, taken in conjunction with theaccompanying drawings, which illustrate, by way of example, theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of a prior art multi-axle transportvehicle for moving heavy loads;

FIG. 2 is a top plan view of the vehicle of FIG. 1;

FIG. 3 a front elevation view of a prior art axle suspension system;

FIG. 4 is a side elevation view of the prior art suspension system;

FIG. 5 is a front elevation view of a suspension system in accordancewith the present invention;

FIG. 6 is a side elevation view of the suspension system;

FIG. 7 is a rear elevation view of the suspension system;

FIG. 8 is a front elevation view of the suspension system with an axlerotated in a clockwise direction;

FIG. 9 is a front elevation view of the suspension system with the axlerotated in a counterclockwise direction;

FIG. 10 is a side elevation view of the suspension system in a fullyretracted position;

FIG. 11 is a side elevation view of the suspension system in amid-stroke position;

FIG. 12 is a side elevation view of the suspension system in a fullyextended position;

FIG. 13 is a side elevation view of the suspension system when the tiresencounter a pothole;

FIG. 14 is a side elevation view of the suspension system when the tiresencounter a bump;

FIG. 15 is a simplified bottom plan view of a prior art axle linkagemember; and,

FIG. 16 is a simplified bottom plan view of the axle linkage member ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 and 2 illustrate side elevation and top plan views,respectively, of a prior art multi-axle transport vehicle 500 for movingheavy loads. The vehicle 500 has a front dolly 502 and a pair of reardollies 504 upon which a load 506 rests. The front dolly 502 and reardollies 504 each have two axles 505 with four tires 507. Axles 505 arerotatable about a vertical pivot axis 509 thereby allowing the axles 505and tires 507 to turn to the right or left. The axles 507 are connectedto the frames of the dollies 502, 504 by a suspension system whichcontrols the vertical movement of the axles 505. A towing vehicle 508such as a tractor pulls transport vehicle 500 using a tow bar 510.

FIGS. 3 and 4 illustrate front elevation and side elevation views,respectively, of a prior art axle suspension system 600. Suspensionsystem 600 includes an upper body 602 which is pivotally connected to anaxle linkage member 604 at point 605. Body 602 is connected to theunderside of a dolly and pivots about vertical axis 606 therebypermitting suspension system 600 to turn. An axle 608 and associatedtires 610 are connected to axle linkage member 604 thereby permittingaxle 608 to roll in response to the road environment (also refer toFIGS. 8 and 9). A single fluid activated cylinder 612 is pivotallyconnected between body 602 and axle linkage member 604. Fluid activatedcylinder 612 usually operates using a combined hydraulic and nitrogengas system which is well known in the art. When cylinder 612 isextended, axle linkage member 604 pivots away from body 602 raising thetop of the dolly further off of the ground (refer to FIG. 12). Whencylinder 612 is retracted, axle linkage member 604 pivots toward body602 lowering the top of the dolly closer to the ground (refer to FIG.10). In typical operation when the transport vehicle is traveling down ahighway, the height of suspension system 600 is set to a mid position byappropriately activating cylinder 612. When the transport vehicle goesover an obstacle such as a large bump or the crest of a hill, suspensionsystem 600 is extended to raise the transport vehicle and therebyprevent possible dragging. Conversely when the transport vehicle goesunder an obstruction such as an overpass, suspension system 600 isretracted to lower the transport vehicle and thereby prevent possiblecollision with the overpass.

Because axle linkage member 604 is connected to body 602 at only onepoint 605, the stresses encountered during travel can cause axle linkagemember 604 and therefore axle 608 to yaw (refer also to FIG. 15 and thediscussion pertaining thereto).

Suspension system 600 is typically designed as a split system so thatdollies on the right side of the transport vehicle can be raised andlowered independently from dollies on the left side of the vehicle.

FIGS. 5–7 illustrate front, side, and rear elevation views,respectively, of a suspension system for a transport vehicle inaccordance with the present invention, generally designated as 20.Suspension system 20 includes a body 22 which is pivotable about a firstnominally vertical axis 24. Body 22 further includes a first attachmentstation 26 spaced apart from a second attachment station 28. In theshown embodiment, body 22 includes first arm 30 and second arm 32 havingdistal ends upon which the first attachment station 26 and secondattachment station 28 are respectively disposed.

An axle 34 is disposable along a second axis 36 which is perpendicularto first axis 24. Axle 34 is nominally aligned with second axis 36.However, axle 34 can pivot or roll with respect to second axis 36 as afunction of the road surface (also refer to FIGS. 8 and 9). Axle 34 hastires 35 disposed at its two ends.

An axle linkage member 38 has a third attachment station 40 spaced apartfrom a fourth attachment station 42. Third attachment station 40 of axlelinkage member 38 is pivotally connected to first attachment station 26of body 22, and fourth attachment station 42 of axle linkage member 38is pivotally connected to second attachment station 28 of body 22. Axlelinkage member 38 is pivotable about a third axis 44 which is parallelto second axis 36.

Axle 34 is pivotally connected to axle linkage member 38 and ispivotable about a fourth axis 46 which is perpendicular to first axis24, second axis 36, and third axis 44 (refer also to FIGS. 8 and 9).

Two spaced apart fluid activated cylinders 48 are pivotally connectedbetween body 22 and axle linkage member 38. The two fluid cylinders 48are disposed outside of first, second, third, and fourth attachmentstations 26, 28, 40, and 42. As defined herein, outside means thatcylinders 48 reside closer to tires 35 than the four attachment stations26, 28, 40, and 42, and that the two cylinders 48 are therefore spacedwider apart than the two pairs of attachment stations.

FIG. 8 is a front elevation view of suspension system 20 with axle 34rotated about axis 46 in a clockwise direction. FIG. 9 is a frontelevation view of suspension system 20 with axle 34 rotated about axis46 in a counterclockwise direction. Such positions would result fromtraveling upon an inclined or crowned road surface.

FIGS. 10–12 are side elevation views of suspension system 20 in fullyretracted, mid-stroke, and fully extended positions, respectively. InFIG. 10, the two fluid activated cylinders 48 are retracted causing axlelinkage member 38 to pivot toward body 22 thereby lowering the transportvehicle. In FIG. 11, the two fluid activated cylinders 48 are in amid-stroke position such as would be useful in traveling down a roadunder nominal conditions. In FIG. 12, the two fluid activated cylinders48 are extended causing axle linkage member 38 to pivot away from body22 thereby raising the transport vehicle.

FIG. 13 is a side elevation view of suspension system 20 traveling alonga road. When the tires 35 encounter a pothole 700, suspension system 20automatically extends from a mid-stroke position on the left side to anextended position in the middle, and returns to a mid-stroke position onthe right side thereby cushioning the ride of the transport vehicle.

FIG. 14 is another side elevation view of suspension system 20 travelingalong a road. When the tires 35 encounter a bump 800, suspension system20 again automatically cushions the ride of the transport vehicle. Inthis case, the suspension retracts from a mid-stroke position on theleft to a retracted position in the middle and returns to the mid-strokeposition on the right.

FIG. 15 is a simplified bottom plan view of the prior art axle linkagemember 604 of FIGS. 3 and 4 which is pivotally connected to axle 608.Since axle linkage member 604 is only connected to body 602 at one point605, forces experienced during driving such as by turning, driving on anincline, going over bumps, going over potholes, etc. can cause axlelinkage member 604 and axle 608 to yaw or rotate horizontally asindicated by the dotted lines so that the axle 608 is no longerperpendicular to the direction of travel. This condition can causeunwanted mechanical stresses and/or vibration particularly at higherspeeds.

FIG. 16 is a simplified bottom plan view of axle linkage member 38 ofthe present invention. In suspension system 20, axle linkage member 38is not just connected to body 22 at one location (see FIGS. 5–7).Rather, axle linkage member 38 has four attachment stations to body 22:left cylinder 48, attachment stations 28/42, attachment stations 26/40,and right cylinder 48. As a result of the four attachment stations, axlelinkage member 38 is rigidly locked in place with respect to body 22 andwill therefore resist the tendency to yaw. Axle 34 is therefore alwayssubstantially perpendicular to the direction of travel. In other words,when the transport vehicle is traveling on a road, connection of firstattachment station 26 to third attachment station 40, connection ofsecond attachment station 28 to fourth attachment station 42, andconnection of two fluid activated cylinders 48 between body 22 and axlelinkage member 38 combine to reduce the yaw of axle 34.

The preferred embodiments of the invention described herein areexemplary and numerous modifications, variations, and rearrangements canbe readily envisioned to achieve an equivalent result, all of which areintended to be embraced within the scope of the appended claims.

1. A suspension system for a transport vehicle, comprising: a bodypivotable about a first axis, said body having a first attachmentstation spaced apart from a second attachment station; an axledisposable along a second axis perpendicular to said first axis; an axlelinkage member having a third attachment station spaced apart from afourth attachment station, said third attachment station of said axlelinkage member pivotally connected to said first attachment station ofsaid body, and said fourth attachment station of said axle linkagemember pivotally connected to said second attachment station of saidbody, said axle linkage member pivotable about a third axis parallel tosaid second axis; said axle pivotally connected to said axle linkagemember, said axle pivotable about a fourth axis perpendicular to saidfirst, second and third axes; two spaced apart fluid activated cylinderspivotally connected between said body and said axle linkage member,wherein said two fluid activated cylinders are disposed outside of saidfirst, second, third, and fourth attachment stations; and, wherein whensaid two fluid activated cylinders are extended, said axle linkagemember pivots away from said body, and when said two fluid activatedcylinders are retracted, said axle linkage member pivots toward saidbody.
 2. A suspension system according to claim 1, further including:when the transport vehicle is traveling on a road, said connection ofsaid first attachment station to said third attachment station, saidconnection of said second attachment station to said fourth attachmentstation, and said connection of said two fluid activated cylindersbetween said body and said axle linkage member reduce yaw of said axle.